【前言】

上一篇博客已经讲解了如何在APP端调用websocket，接收消息和发送消息。点击直达
接下来讲解一下websocket的服务端如何写。websocket的服务端，简单说就是创建链接，然后接收消息，发送消息，关闭链接。
当然发送消息的方法也可以当做一个普通的方法被其他类调用。

【正文】

pom文件引入依赖

 <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-websocket-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>

创建websocket实现类

连接websocket

    @OnOpen
    public void onOpen(Session session){
		 log.info("webSocket消息，有新的连接");
        this.session = session;
        webSocketSet.add(this);

    }

关闭websocket

    @OnClose
    public void onClose(){
        try {
            session.close();
        } catch (IOException e) {
            log.error("关闭链接异常",e);
        }finally {
            try {
                session.close();
            } catch (IOException e) {
                log.error("关闭链接异常finally方法",e);
            }
            webSocketSet.remove(this);
        }
        log.info("webSocket消息，连接断开");
    }

接收消息

    @OnMessage
    public void onMessage(String message){
      		 log.info("webSocket消息，收到客户端发来的消息",message);
       		//调用发送消息方法
            sendMessage(message);
    }

发送消息

    public void sendMessage(String  message){
        for (WebSocket webSocket: webSocketSet){
            try {
                webSocket.session.getBasicRemote().sendText(message);
            }catch (Exception e){
                log.error("发送消息异常",e);
                log.error("在线连接的数量："+webSocketSet.size());
                // 关闭session
                //添加到需要移除的集合中
                webSocketSeterror.add(webSocket);
            }
        }
        //循环移除掉报错的链接
        for (WebSocket w :webSocketSeterror) {
            webSocketSet.remove(w);
        }
        //将报错的链接清除
        if(webSocketSeterror.size() > 0 ){
            log.error("需要移除的session对象个数："+webSocketSeterror.size());
        }
        webSocketSeterror.clear();
    }

全部代码

package com.tfjy.arprobackend.service;

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import javax.websocket.OnClose;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;

/**
 * @ClassName WebSocket
 * @Description WebSocket实现（一个特殊的service）
 * @Author 
 * @Date
 * @Version 
 */
@Component
@ServerEndpoint("/webSocket")
@Slf4j
public class WebSocket {
    private Session session;

    private static CopyOnWriteArraySet<WebSocket> webSocketSet = new CopyOnWriteArraySet<>();
    private static CopyOnWriteArraySet<WebSocket> webSocketSeterror = new CopyOnWriteArraySet<>();


    @OnOpen
    public void onOpen(Session session){
        this.session = session;
        webSocketSet.add(this);
//        log.info("webSocket消息，有新的连接");
    }

    @OnClose
    public void onClose(){
        try {
            session.close();
        } catch (IOException e) {
            log.error("关闭链接异常",e);
        }finally {
            try {
                session.close();
            } catch (IOException e) {
                log.error("关闭链接异常finally方法",e);
            }
            webSocketSet.remove(this);
        }
//        log.info("webSocket消息，连接断开");
    }

    @OnMessage
    public void onMessage(String message){
//        log.info("webSocket消息，收到客户端发来的消息",message);

            sendMessage(message);
    }

    public void sendMessage(String  message){
        for (WebSocket webSocket: webSocketSet){
            try {
                webSocket.session.getBasicRemote().sendText(message);
            }catch (Exception e){
                log.error("发送消息异常",e);
                log.error("在线连接的数量："+webSocketSet.size());
                // 关闭session
                //添加到需要移除的集合中
                webSocketSeterror.add(webSocket);
            }
        }
        //循环移除掉报错的链接
        for (WebSocket w :webSocketSeterror) {
            webSocketSet.remove(w);
        }
        //将报错的链接清除
        if(webSocketSeterror.size() > 0 ){
            log.error("需要移除的session对象个数："+webSocketSeterror.size());
        }
        webSocketSeterror.clear();
    }
}

其他类调用websocket发送消息

直接调用websocket实现类的sendMessage方法就可以了。

 // 发送webSocket消息
        webSocket.sendMessage(activityParameterModel.getCourseId() + activityParameterModel.getClassId() + CommonConfigurationUtils.SUCCESS);